I have a 75 foot roll of LMR-400 and need to go about 90 feet with it. Will it cause any problems if I screw in a 15-20' length of coax. The total length is going from a multi-band dipole to a FT-950 (100 watts max)and I have both an internal and external antenna tuner. Thanks.

Shouldn't hurt any thing at lower frequencies, but more feed line than you need and barrel connectors are asking for loss at higher frequencied; e.g. 10 meters. Make sure you have the connection water proofed and add some strain relief.

Should not cause any problems...I've done exactly this in a couple of antenna installations. Spray the barrel connector and PL-259's with an anti-oxident and wrap the entire assembly with Coax Seal or Silicone Tape.

As Mark said, if it's a fan dipole, no problem. If it's a single wire multiband dipole, the power lost to the barrel connector is peanuts compared to the power lost feeding a multiband dipole with coax.

To state the obvious, which nobody has yet , the splice , all things being equal , should go at the end near the ground .It may give years of trouble free service , but when you need to get to it, it's better if it's NOT up the tower.

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